A kringle-containing protease with plasminogen-like activity in the basal chordate Branchiostoma belcheri
A kringle-containing protease with plasminogen-like activity in the basal chordate Branchiostoma belcheri
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DOI：
10.1042/bsr20080173
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发表时间：
2009-12-01
影响因子：
4
通讯作者：
Zhang, Shicui
中科院分区：
文献类型：
--
作者：
Liu, Mingying;Zhang, Shicui
猪纤维蛋白溶酶原（plasminogen）是丝氨酸蛋白酶超家族的成员之一，是构成纤溶系统的关键成分，其进化起源在动物进化过程中一直是个未知数。在本研究中，我们分离到一个cDNA，命名为BbPlgl，编码一个含有Kringle蛋白酶与纤溶酶原样活性的基础脊索动物Branchiostoma belcheri。BbPlgl蛋白由430个氨基酸组成，其结构特征是N端有一个16个氨基酸的信号肽，2个kringle结构域和一个丝氨酸蛋白酶结构域，（组织纤溶酶原激活物）-裂解位点（在Arg（297）和瓦尔（298）之间），预期用于蛋白酶功能的催化三联体His（237）-Asp（288）-Ser（379），和潜在的Winked糖基化位点，都是猪的特征。此外，重组复性BbPlg 1蛋白能被人尿激酶型纤溶酶原激活剂（uPA）激活，并具有猪样活性。BbPlgl还能够在中性和碱性pH下在4 ° C下在不添加uPA的情况下自动活化，并且通过添加人uPA加速活化。这些结果表明，BbPlgl是猪家族的新成员，具有K-K-SP（kringle-kringle-serine protease）结构域结构，缺乏PAN结构域，将猪的进化起源推到原脊索动物。此外，BbPlgl在B中显示组织特异性表达模式。belcheri基因在肝盲囊和后肠中的表达量最高，这与文昌鱼肝盲囊是脊椎动物肝脏的前身的观点一致。
Pig (plasminogen), a member of the serine protease superfamily, is a key component constituting the fibrinolytic system, and its evolutionary origin remains unknown during the course of animal evolution. In the present study, we isolated a cDNA, designated BbPlgl, encoding a kringle-containing protease with plasminogen-like activity from the basal chordate Branchiostoma belcheri. The deduced protein, BbPlgl, consisted of 430 amino acids, which is structurally characterized by the presence of an N-terminal signal peptide of 16 amino acids, 2 kringle domains with a Lys-binding site structure, a serine protease domain with the putative tPA (tissue plasminogen activator)-cleavage site (between Arg(297) and Val(298)), the catalytic triad His(237)-Asp(288)-Ser(379) expected for protease function, and a potential Winked glycosylation site, all characteristic of Pigs. Besides, the recombinant refolded BbPlgl was readily activated by human uPA (urokinase plasminogen activator), and exhibited Pig-like activity. BbPlgl was also able to auto-activate at neutral and alkaline pH at 4 degrees C without the addition of uPA, and the activation was accelerated by addition of human uPA. These results demonstrate that BbPlgl is a novel member of the Pig family, with a domain structure of K-K-SP (kringle-kringle-serine protease) lacking the PAN domain, pushing the evolutionary origin of Pig to the protochordate. In addition, BbPlgl displays a tissue-specific expression pattern in B. belcheri, with the most abundant expression in the hepatic caecum and hind-gut, agreeing with the notion that the hepatic caecum of amphioxus is the precursor of the vertebrate liver.